Polyvinyl acetal resin sheets containing amyl succinate



Patented Nov. 12,1940

, UNITED STATES POLm ACETAL nnsm snnn'rs CON- TAINING AMYL SUCCINATE 1Donaldllt. Swan, Rochester, N. Y assignor to Eastman Kodak Company,Rochester, N. Y.,a corporation of New Jersey No Drawing. ApplicationDecember 14, 1939,

Serial No. 309,235

, l'Claim.

This invention relates to polyvinyl acetal resin sheets, and moreparticularly to sheets suitable for the manufacture of safety glass.

One object of my invention;is to produce com- '5 positions of matterwhich can be made into permanently transparent sheets-suitable for usein laminated, shatter-proof glass. Another obiectvis to producecompositions which can be rolled, extruded, molded, or otherwise worked10 into relatively thick sheets and massive plastics.

Otherobjectswill hereinafter appear.

I have discovered that amyl succinate is a useful plasticizer forcertain polyvinyl acetal then be extruded through an annular die, and

resins, namely the polyvinyl butyraldehyde l5 acetal resins. Moreover, Ihave discovered that when 40.0:- more parts of amyl succinate is used.with 100 parts of polyvinyl butyraldehyde acetal resin, an unusual andremarkable eilect is obtained which I may call elasticizing. That is soto say, a sheet of polyvinyl butyraldehyde' acetal resin containingabout 40 or more parts amyl succinate per 100 partsmi resin possessesthe property which, in therubber industry. is known,

as nerve": namely, the property of stretching 25 to a considerableextent when tension is exerted upon it, and returning to its originaldimensions when the tension is released. This property renders su'chsheets, which I shall call rubber? sheets, particularly useful inthemanufacture of 80 shatter-proof glass. a

Sheets for use in laminatedgiass may be made by dissolving the polyvinylbutyraldehyde acetal resin and the amyl succinate in'a suitable volatilesolvent or solvent mixture, such, for instance. as 85 acetone, methanol,acetone-methanol mixtures, ethylene chlorideamethanol mixtures, etc.,about 300 to 500 or more parts of the solvent or solvent mixture beingused per lOO'parts oi the resin.

Th solution is then cast as a sheet, the volatile '40 solventevaporated, and the sheet stripped from the casting surface. 7

and .Ernest C. Blackard, filed June l2, 1937.-

For example, 40 or more parts 01 amyl succinate and- 100 parts of 'apolyvinyl butyraldehyde acetal resin may be mixed in a suitable,jacketed mixer at a low temperature, for example 10 C., and the mixturemay then be worked on hot rolls, 10 in the manner described in U.S.'Patent 2,048,686 of F. R. Conklin, until complete homogenization hastaken place. The mass thus produced may the tube so formed slit to forma sheet. The polyvinyl acetal resins can be prepared by reactingpolyvinyl alcohol with an aldehyde in the presence of an acetalcondensation catalyst,

e. g. a mineral acid. These resins can also be prepared by 7simultaneously de-esterifying a amples 1, 2, a and 4; and British Patent459,878,

Examples 1, 2, 5, 6, '7, 8, 9 and 10.

What I claim as my invention and desire to be secured by Letters Patentof the United as States is: g A transparent rubbery sheet comprising 100parts of a polyvinyl butyraldehyde acetal resin and at least 40 parts,approximately, of amyl succinate. 40

DONALD R. SWAN.

